Editing Iron(III) oxide (section)

{{short description|Chemical compound}}
{{About|a red-colored oxide of iron|other uses|Red iron (disambiguation){{!}}Red Iron}}
{{Use dmy dates|date=January 2021}}
{{chembox
| Verifiedfields = changed
| Watchedfields = changed
| verifiedrevid = 464185021
| Name = Iron(III) oxide
| ImageFile = Haematite-unit-cell-3D-balls.png
| ImageName = Haematite unit cell
| ImageCaption = {{colorbox|#514d7c}} [[Iron|Fe]] {{colorbox|#b20000}} [[Oxygen|O]]
| ImageFile1 = Iron(III)-oxide-sample.jpg
| ImageName1 = Sample of iron(III) oxide
| ImageFile2 = Pourbaix_Diagram_of_Iron.svg
| ImageName2 = Pourbaix Diagram of aqueous Iron
| IUPACName = Iron(III) oxide
| OtherNames = ferric oxide, [[haematite]], ferric iron, red iron oxide, rouge, [[maghemite]], colcothar, iron sesquioxide, [[rust]], [[ochre]]
| SystematicName = 
| Section1 = {{Chembox Identifiers
| CASNo = 1309-37-1
| CASNo_Ref = {{cascite|correct|CAS}}
| ChemSpiderID_Ref = {{chemspidercite|changed|chemspider}}
| ChemSpiderID = 14147
| UNII = 1K09F3G675
| UNII_Ref = {{fdacite|correct|FDA}}
| ChEBI = 50819
| ChEBI_Ref = {{ebicite|correct|EBI}}
| SMILES = O1[Fe]2O[Fe]1O2
| PubChem = 518696
| RTECS = NO7400000
| KEGG = C19424
| KEGG_Ref = {{keggcite|changed|kegg}}
| InChI = 1/2Fe.3O/rFe2O3/c3-1-4-2(3)5-1
| InChIKey = JEIPFZHSYJVQDO-ZVGCCQCPAC
| StdInChI_Ref = {{stdinchicite|correct|inchi}}
| StdInChI = 1S/2Fe.3O
| StdInChIKey_Ref = {{stdinchicite|correct|inchi}}
| StdInChIKey = JEIPFZHSYJVQDO-UHFFFAOYSA-N
| EC_number = 215-168-2
| Gmelin = 11092
  }}
| Section2 = {{Chembox Properties
| Fe=2 | O=3
| Appearance = Red solid
| Odor = Odorless
| Density = 5.25 g/cm<sup>3</sup><ref name=crc/>
| MeltingPtC = 1539
| MeltingPt_ref = <ref name=crc>[[#Haynes|Haynes]], p. 4.69</ref><br /> decomposes<br /> {{convert|105|C|F K}}<br /> β-dihydrate, decomposes<br /> {{convert|150|C|F K}}<br /> β-monohydrate, decomposes<br /> {{convert|50|C|F K}}<br /> α-dihydrate, decomposes<br /> {{convert|92|C|F K}}<br /> α-monohydrate, decomposes<ref name=doc00>{{cite book|page = 433|title = A Dictionary of Chemical Solubilities: Inorganic|edition = 2nd|first1 = Arthur Messinger|last1 = Comey|first2 = Dorothy A.|last2 = Hahn|place = New York|publisher = The MacMillan Company|date = February 1921|url=https://archive.org/details/dictionaryofchem00comerich/page/436/mode/2up }}</ref>
| Solubility = Insoluble
| SolubleOther = Soluble in diluted [[acid]]s,<ref name=crc /> barely soluble in [[sugar]] solution<ref name=doc00/><br /> Trihydrate slightly soluble in aq. [[tartaric acid]], [[citric acid]], [[acetic acid]]<ref name=doc00 />
| MagSus = +3586.0x10<sup>−6</sup> cm<sup>3</sup>/mol
| RefractIndex = n<sub>1</sub>&nbsp;=&nbsp;2.91, n<sub>2</sub>&nbsp;=&nbsp;3.19 (α, hematite)<ref>[[#Haynes|Haynes]], p. 4.141</ref>
}}
| Section3 = {{Chembox Structure
| CrystalStruct = [[Rhombohedral lattice system|Rhombohedral]], [[pearson symbol|hR30]] (α-form)<ref name=odnpa>{{cite book|page = 167|url = https://books.google.com/books?id=sY-0IGwimWkC&pg=PA167|title = One-Dimensional Nanostructures: Principles and Applications|editor-first = Tianyou|editor-last = Zhai|editor-first2 = Jiannian|editor-last2 = Yao|year = 2013|place = Hoboken, New Jersey|isbn = 978-1-118-07191-5|publisher = John Wiley & Sons, Inc.|first1 = Yichuan|last1 = Ling|first2 = Damon A.|last2 = Wheeler|first3 = Jin Zhong|last3 = Zhang|first4 = Yat|last4 = Li}}</ref><br /> [[cubic crystal system|Cubic]] bixbyite, cI80 (β-form)<br /> Cubic spinel (γ-form)<br /> [[orthorhombic crystal system|Orthorhombic]] (ε-form)<ref name="atmilab" />
| SpaceGroup = R3c, No. 161 (α-form)<ref name=odnpa /><br /> Ia{{overline|3}}, No. 206 (β-form)<br /> Pna2<sub>1</sub>, No. 33 (ε-form)<ref name="atmilab" />
| PointGroup = 3m (α-form)<ref name=odnpa /><br /> 2/m {{overline|3}} (β-form)<br /> mm2 (ε-form)<ref name="atmilab" />
| Coordination = [[octahedral molecular geometry|Octahedral]] (Fe<sup>3+</sup>, α-form, β-form)<ref name=odnpa />
  }}
| Section4 = {{Chembox Thermochemistry
| Thermochemistry_ref =<ref name=crc2>[[#Haynes|Haynes]], p. 5.12</ref>
| DeltaHf = −824.2 kJ/mol<ref name=crc2 />
| DeltaGf = −742.2 kJ/mol<ref name=crc2 />
| Entropy = 87.4 J/mol·K<ref name=crc2 />
| HeatCapacity = 103.9 J/mol·K<ref name=crc2 />
  }}
| Section5 = 
| Section6 = 
| Section7 = {{Chembox Hazards
| GHSPictograms = {{GHS07}}<ref name="sigma">{{Sigma-Aldrich|id=529311|name=Iron(III) oxide|accessdate=2014-07-12}}</ref>
| GHSSignalWord = Warning
| HPhrases = {{H-phrases|315|319|335}}<ref name="sigma" />
| PPhrases = {{P-phrases|261|305+351+338}}<ref name="sigma" />
| NFPA-H = 0
| NFPA-F = 0
| NFPA-R = 0
| NFPA-S = 
| NFPA_ref = <ref name=leker >{{cite web|url = http://www.lesker.com/msds/pdfs/cd72f997d54d3bc42d09a34d6bdca56ebf2ea7fd3a31f08843ec5bd413.pdf|title = SDS of Iron(III) oxide|date = 2012-01-05|publisher = Kurt J Lesker Company Ltd.|place = England|access-date = 2014-07-12|website = KJLC}}</ref>
| TLV-TWA = 5&nbsp;mg/m<sup>3</sup><ref name=crc />
| LD50 = >10 g/kg (rats, oral)<ref name=leker />
| PEL = TWA 10 mg/m<sup>3</sup><ref name=PGCH>{{PGCH|0344}}</ref>
| IDLH = 2500 mg/m<sup>3</sup><ref name=PGCH/>
| REL = TWA 5 mg/m<sup>3</sup><ref name=PGCH/> 
  }}
| Section8 = {{Chembox Related
| OtherAnions = [[Iron(III) fluoride]]
| OtherCations = [[Manganese(III) oxide]]<br /> [[Cobalt(III) oxide]]
| OtherFunction = [[Iron(II) oxide]]<br /> [[Iron(II,III) oxide]]
| OtherFunction_label = [[iron oxides]]
  }}
}}
[[File:Железный сурик.jpg|alt=Vial with iron(III) oxide|thumb|Iron(III) oxide in a vial]]
'''Iron(III) oxide''' or '''ferric oxide''' is the [[inorganic compound]] with the formula {{chem2|Fe2O3}}. It occurs in nature as the mineral [[hematite]], which serves as the primary source of iron for the steel industry. It is also known as '''red iron oxide''', especially when used in [[pigment]]s.

It is one of the three main [[oxide]]s of [[iron]], the other two being [[iron(II) oxide]] (FeO), which is rare; and [[iron(II,III) oxide]] ({{chem2|Fe3O4}}), which also occurs naturally as the mineral [[magnetite]]. 

Iron(III) oxide is often called [[rust]], since rust shares several properties and has a similar composition; however, in chemistry, rust is considered an ill-defined material, described as hydrous ferric oxide.<ref>{{Cite web|last=PubChem|title=Iron oxide (Fe2O3), hydrate|url=https://pubchem.ncbi.nlm.nih.gov/compound/61560|access-date=2020-11-11|website=pubchem.ncbi.nlm.nih.gov|language=en}}</ref>

Ferric oxide is readily attacked by even weak [[acid]]s. It is a weak [[oxidising agent]], most famously when reduced by [[aluminium]] in the [[thermite]] reaction.